1. Field of the Invention
The present invention relates to a patch forming device for forming patches to be used for visually investigating output characteristic of an image forming device.
2. Description of Related Art
Conventional image forming devices that are capable of multitone printing with relatively high quality execute an operation referred to as “color calibration.” Color calibration is performed in order to match density levels indicated by print data received from a high-order program with the density levels measured in images actually printed by the image forming device.
Japanese Patent Application Publication No. 2000-184220 discloses one type of visual calibration.
According to this visual calibration, densities of magenta and black are first adjusted. Next, a test chart is prepared by printing a plurality of gray patches from the mixture of magenta, yellow, and cyan and by printing a gray area surrounding the patches from black only. The density of cyan is changed in the lateral axial direction and the density of yellow is changed in the vertical axial direction. A user views the test chart and selects the patch with the optimum gray balance, that is, the patch with the best balance between the three color agents of cyan, yellow, and magenta.